Specific chromosomal rearrangements, predominantly translocations and inversions, are observed in the great majority of human hematopoietic malignancies. In Burkitt lymphoma the specific chromosomal translocations result in the juxtaposition of one of the three human immunoglobulin loci and the c-myc oncogene. In diffuse B-cell lymphomas, multiple myelomas and chronic lymphocytic leukemias of the B-cell type carrying the t(11;14) (q13;q32) chromosome translocation, the bcl-1 locus is translocated to the heavy-chain locus on chromosome 14. In most cases of follicular lymphoma, one of the most common human hematopoietic malignancies, a (t14;18) (q32;q21) chromosome translocation has been observed. This translocation moves the bcl-2 gene to a position adjacent to the heavy-chain locus. In one cell line derived from a leukemic patient having both a t(14;8) and a t(14;18) translocation enhanced mRNA production from the bcl-2 gene was observed. (Tsujimoto et al, Science, Vol. 228, pages 1440-1443 (1985).) It was concluded there that the transcription unit of the bcl-2 gene spans the chromosome break-point, and thus the oncogene protein is likely to be structurally altered in the B-cell neoplasms. Surprisingly, it has now been found that the translocation does not alter the oncogene protein itself, as the translocation break-points occur downstream from the actual protein coding sequences. Thus oncogenesis may be solely due to the overproduction of the normal human gene products of the bcl-2 gene.
Effective treatment for cancer is often dependent upon an early and proper diagnosis of the malignancy. There is thus a need for simple and accurate diagnostic methods for detecting and identifying human malignancies, such as lymphomas, in general, and follicular lymphomas in particular.